The present invention relates to a microwave oven, and more particularly to a microwave oven having a conducting member for controlling the supply of electrical power, which is capable of simplifying a structure of the switching system, according to controlling the electrical power supplied to a high voltage transformer by using a conducting member installed in a door.
FIG. 1 shows a microwave oven for heating/cooking food using microwaves. The microwave oven contains a case 20 for forming a cooking chamber 22, a door 21 for opening/closing the cooking chamber 22, a tray 24 being installed in the cooking chamber 22, and a panel 25 for controlling operations of the microwave oven.
FIG. 2 is a partial cutaway view of FIG. 1. A pair of latch hooks 28a, 28b are installed in the door 21, catch openings 27a, 27b are formed corresponding to each latch hook 28a, 28b at a front plate 26 of the case 20. If the door 21 is pushed shut, the latch hooks 28a, 28b will engage the catch openings 27a, 27b to hold the door 21 shut.
At the back side of the panel 25 is provided a device chamber (not shown). In the device chamber are installed a magnetron for generating microwaves and a high voltage transformer HVT for generating a high voltage supplied to the magnetron, and so on. In supplying an AC power to the high voltage transformer HVT, this high voltage transformer HVT generates a predetermined high voltage to drive the magnetron. Then, the magnetron radiates microwaves of about 2,450 MHz frequency to heat/cook food.
As shown in FIG. 2, micro switches MS1, MS2, MS3 are installed at the back side of the front plate 26 of the case 20. FIGS. 3a and 3b are schematic diagrams and symbols of each micro switch MS1, MS2, MS3, respectively. The micro switches MS1, MS2, MS3 have a slight interval at the point of contact, and a mechanism of a snap action. The micro switches MS1, MS2, MS3 have a mechanism at the point of contact to open/close by the determined operation and force in a sealing case, and is a small switch for arranging a pushing mechanism of the actuator switch located on the outside of the case. That is, the micro switch is one of the contact type detectors, which detects something contacted according to releasing the inside point of contact when something 6 closes to a push button 1, and begins to push the push button 1, and applies more than a predetermined force F to the push button 1. In FIG. 3a, the reference numeral 2 is a movable spring, and the reference numeral 3 is a movable point of contact. The reference numeral 4 is a fixed point b of contact, and the reference numeral 5 is a fixed point a of contact. COM, NO, and NC are a common terminal, a normally open terminal, and a normally closed terminal, respectively. In FIG. 3b, a point a of contact 7 is the point of contact which conducts first when the micro switch is operated, and which connects the common terminal COM into the normally open terminal NO. A point b of contact 8 is the point of contact which conducts when the micro switch is not operated, and which connects the common terminal COM into the normally close terminal NC.
The micro switches MS1, MS2, MS3 each have an operating button 31, 32, 33, respectively. At the back side of the front plate 26 are installed a pair of movable members 29a, 29b to adjoin the catch openings 27a, 27b. Then, the movable members 29a, 29b are fixed for pivoting by each pin 23a, 23b, and are fixed elastically by each spring 41a, 41b. 
In FIG. 2, if the door 21 is pushed closed, the micro switches MS1, MS2, MS3 are operated by the latch hooks 28a, 28b which are inserted in the catch openings 27a, 27b. That is, when the movable members 29a, 29b are pushed by each latch hook 28a, 28b, the movable members 29a, 29b are rotated against the elasticity of the springs 41a, 41b. Therefore, the operating button 31 is pushed by the upper movable members 29a, and the operating buttons 32, 33 are pushed by the lower movable members 29a, respectively.
Meanwhile, since the conventional microwave oven has been made to be operated using the AC common power source of 110V/220V for supplying high alternating current, the microwave oven cannot be used in a place where alternating current is not available.
To overcome the above described problem, an AC/DC type microwave oven has been developed, as shown in FIG. 4. In FIG. 4, an AC/DC type microwave oven includes an AC driving load 30, a DC driving load and DC/AC converting part 40, and a microwave oscillator 50. The AC driving load 30 is driven by an AC input power. The DC driving load and DC/AC converting part 40 includes the DC driving load being driven by a DC input power, and the DC/AC converter converting the DC input power into an AC power. The microwave oscillator 50 is supplied by only one of the AC input power or the DC/AC power converted by a DC/AC converter, and generates microwaves.
The AC driving load 30 is driven by alternating current, which includes a lamp and a fan motor, etc., which are connected to the AC power source. A power switch (not shown) to determine the supplying status of AC is connected to the AC power source. The DC driving load being driven by direct current, which includes a lamp and a fan motor, etc., which are connected to the DC power source. A power switch (not shown) to determine the supplying status of DC is connected to the DC power source. The direct current forms a differential DC circuit net discriminated as an AC circuit net. Then, the direct current is connected to the input side of the DC/AC converting part 40 which supplies alternating current. The microwave oscillator 50 includes a high voltage transformer HVT which receives the AC power, a high voltage condenser HVC, a high voltage diode HVD, and a magnetron MGT. The operation of the microwave oscillator 50 is described the same way as shown in FIG. 1.
Therefore, as the AC power source supplies alternating current to the AC driving load 30, and as the DC power source supplies direct current to the DC driving load and DC/AC converting part 40, respectively, the conventional AC/DC type microwave oven is operated.
That is, in case the large amount of current is supplied through the micro switches MS1, MS2, the points of contact of the micro switches MS1, MS2 can remain in the contacting status. When the user pulls the door 21 so that the cooking chamber is open, the operating buttons 31, 32 of the micro switches MS1, MS2 can remain in the pushed status. Accordingly, as the primary switch PC and secondary switch SD of the DC driving load and DC/AC converting part 40 are held in the closed status, current is supplied to the DC driving load and DC/AC converting part 40, so the AC/DC type microwave oven has the problem of encountering a malfunction.
According as the primary switch PC and secondary switch SD of the DC driving load and DC/AC converting part 40 are held there closed status, and then current is supplied to the DC driving load and DC/AC converting part 40, so the AC/DC type microwave oven has the problem of encountering a malfunction.
FIG. 5 is a block diagram of a conventional AC/DC type microwave oven operated by many micro switches. For preventing the threat of electromagnetic waves, the microwave oven is capable of isolating the supply of the power not to generate electromagnetic waves when the door 21 is open. For insuring the isolation of the supply of power, the microwave oven includes many micro switches PA, SA, MA, PD, SD, MD for multi-switching operations.
The structure of the microwave oven, however, becomes very complicated by many micro switches PA, SA, MA, PD, SD, MD, and by the peripheral parts for driving the micro switches. Furthermore, as the number of parts of the microwave increases, the manufacturing cost of the microwave oven increases.
The present invention has been made to overcome the above described problem of the prior art, and accordingly it is the first objective of the present invention to provide a microwave oven for simplifying the structure by operating multi-switching using a more simplified structure of a switching system.
It is the second objective of the present invention to provide an AC/DC type microwave oven for preventing faulty switching operations by large amounts of current when the DC input power source is used.
To achieve the above objectives, the present invention provides a microwave oven having a conducting member for controlling the supply of electrical power. In a microwave oven having a case forming a cooking chamber, a door for opening/closing the chamber, a high voltage transformer for generating a high voltage, and a magnetron for generating microwaves driven by the high voltage being output from the high voltage transformer, the microwave oven includes: a pair of terminal members being connected between an electrical power source and the high voltage transformer, in which the terminal members are remote-located, respectively; and a conducting member for being installed in the door to reveal the ends of the conducting member on one side of the door, and for being connected electrically to the terminal members as the ends of the conducting member are contacted to the terminal members, respectively.
A pair of latch hooks is formed in the door, and a pair of catch openings into which the latch hooks are inserted is formed at the front of the case; the ends of the conducting members are contacted to the terminal members when the latch hooks are inserted into the catch openings, accordingly, as the ends of the conducting member are revealed at one end of the latch hooks.
According to the embodiment of the present invention, the electrical power source is a direct current power source for supplying direct current; and means for converting the direct current into alternating current intervenes between the direct current power source and the high voltage transformer.
The means for converting includes: a commutator containing a commutator case formed almost cylindrical in appearance and made of insulated materials, for containing one or more pair of conducting parts for being remote-contacted to the outer circle side of the commutator case at each determined interval; a motor for rotating the commutator; a pair of input brushes for applying the direct current to the commutator according to being contacted to the outer circle side of the commutator, respectively; and a pair of output brushes for converting/producing the direct current supplied by the input brushes into alternating current, when the commutator rotates according to being contacted to the outer circle side of the commutator, respectively.
To achieve the above objective, the present invention provides an AC/DC type microwave oven having a conducting member for controlling the supply of electrical power. In an AC/DC type microwave oven for supplying a microwave oscillator with direct current or alternating current, the AC/DC type microwave oven includes: a pair of terminal members being connected between the high voltage transformer and the AC or DC supply of electrical power, wherein the terminal members are remote-located, respectively; and a conducting member for being installed in a door to reveal ends of the conducting member on one side of the door, and for connecting electrically to the terminal members by contacting the ends of the conducting member to the terminal members, respectively, when the door is closed.
Accordingly, since the simplified structure of the microwave oven is supplied, the microwave oven can be prevented from encountering faulty switching operation generated by means of large amounts of current supplied from direct current when the DC input power source is used.